Collaborative Research: P2C2--Western United States Hydroclimate during the Last Interglacial: Developing Proxy Records and Using Model Intercomparison to Glimpse the Future

合作研究：P2C2——末次间冰期美国西部水文气候：开发代理记录并利用模型比对展望未来

• 批准号: 2102884
• 负责人: Jessica Oster
• 金额: $ 29.19万
• 依托单位: Vanderbilt University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-09-01 至 2024-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2102884&HistoricalAwards=false
• 关键词: Collaborative; Research; P2C2; Western; United

Freshwater availability is critical to agricultural, energy and urban systems in the arid to semi-arid western U.S. Quantifying hydroclimate change during past warm periods, such as the Last Interglacial (LIG; ~129,000-116,000 years before present), is essential for evaluating climate model simulations of Earth’s past. This project aims to reconstruct variations in the spatial and seasonal distribution of precipitation in the western U.S. during the LIG during which global temperature are comparable to low-end 21st century projections. The project will include the application of novel methods (calcium and triple oxygen isotopes) on stalagmites from Lake Shasta Caverns (northern California) and Titan Cave (northern Wyoming), and will provide new chronological data and novel measurements (carbonate clumped and triple oxygen isotopes) at four lake sites in the northeast Great Basin (Bear Lake, Utah/Idaho and Bonneville Basin, Utah/Nevada), and southwest Great Basin/Mojave Desert (Lake Manix and Owens Lake, California). The anticipated results of this project are past records of changes in temperature, rainfall amount and moisture source and seasonality. These new past climate records will be integrated into a regional proxy-data network used to benchmark climate model simulations of the Last Interglacial period (127 ka).The paleoclimate modeling intercomparison (PMIP4) and coupled model intercomparison project (CMIP6) efforts of the climate modeling community include Tier 1 LIG (127ka) simulations as a benchmarking target for models with similar CO2 levels, different orbital configuration, unchanged topography and higher sea level. The validation of hydroclimate-relevant variables at a regional scale using climate models requires robustly dated and spatially distributed paleoclimate observations in order to place the LIG water cycle in the western U.S. in the context of geologic and future climate change. Yet, few quantitative estimates of paleoclimate exist for this interval, which offers geochronologic challenges too as it is beyond the limit of radiocarbon age control. This project seeks to improve our understanding of LIG climate in the western U.S. by providing: 1) new observations from speleothem records, 2) new U-Th dating of existing lake cores, and 3) the application of novel semi-quantitative proxies for temperature, precipitation and humidity to speleothems and lake sediments. Through the development of new high-resolution proxy time-series from speleothems and lake sediments, we will provide new insight into the behavior of the North American Monsoon during a past warm period and reconstruct hydroclimatic response to abrupt climatic events during the penultimate deglaciation (Termination II) and Marine Isotope Stage 5 (MIS5). The research uses existing lake cores recovered and archived by previous NSF- and USGS-funded continental drilling projects, and recently collected speleothems known to span much of MIS5 and the LIG.The potential Broader Impacts include quantifying regional hydroclimate changes during past warm periods and benchmarking of climate model simulations for the last interglacial. Other Broader Impacts include translating the project research outcomes via a workshop (paleo to policy) convening water resource managers, government agencies (e.g., USGS), climate and weather risk assessment and projection companies and early career paleoclimate researchers from across the U.S. This workshop will emphasize on the information that terrestrial past climate records (lake sediments, tree rings, speleothems) can provide in terms of hydroclimate data beyond the instrumental records needed by policy makers to assess climate variability and extreme events such as drought and floods. The researchers will produce a white paper, policy briefs for water resource managers and a presentation at an education and outreach session at a scientific meeting (American Geophysical Union). The project will provide scientific training, mentorship and professional development for two graduate students and one postdoctoral researcher. Through joint field trips and collaborations, these students and postdoc will have opportunities to develop interdisciplinary expertise in climate archives, novel proxy systems, geochronology and model-proxy comparison. In addition, the researchers will recruit undergraduate students to complete summer internships related to the project. The undergraduate students will be recruited through (1) the Earth Horizons program and partnership between Vanderbilt University and Tennessee State University, a Historically Black University (HBCU); (2) the Leadership Alliance program at Brown University funded through NSF-REU-EPSCOR. The undergraduate students will be encouraged to develop their research into presentations at regional, national and international scientific meetings (e.g., AGU, GSA).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

淡水供应对美国西部干旱到半干旱地区的农业、能源和城市系统至关重要。在过去温暖时期（如末次间冰期（LIG;距今约129，000 - 116，000年））量化水文气候变化对于评估地球过去的气候模型模拟至关重要。该项目旨在重建LIG期间美国西部降水的空间和季节分布变化，在LIG期间，全球温度与21世纪世纪低端预测相当。该项目将包括新方法的应用（钙和三重氧同位素）对沙斯塔湖洞穴石笋的影响（北方加州）和泰坦洞穴（北方怀俄明州），并将提供新的年代数据和新颖的测量（碳酸盐结块和三重氧同位素）在东北大盆地的四个湖泊网站（熊湖，犹他州/爱达荷州和博内维尔盆地，犹他州/内华达州），和西南大盆地/莫哈韦沙漠（曼尼克斯湖和欧文斯湖，加州）。该项目的预期结果是过去温度、降雨量和水分来源以及季节性变化的记录。这些新的过去气候记录将被整合到一个区域代理数据网络中，用于对末次间冰期（127 ka）的气候模式模拟进行基准测试。气候模拟界的古气候模拟相互比较（PMIP 4）和耦合模式相互比较项目（CMIP 6）的努力包括将Tier 1 LIG（127 ka）模拟作为具有相似CO2水平的模式的基准目标，不同的轨道配置、不变的地形和更高的海平面。水文气候相关变量在区域尺度上使用气候模型的验证需要强大的日期和空间分布的古气候观测，以放置在美国西部的LIG水循环的地质和未来的气候变化的背景下。然而，很少有定量估计的古气候存在的时间间隔，这也提供了地质年代学的挑战，因为它超出了放射性碳年龄控制的限制。该项目旨在通过提供以下内容来提高我们对美国西部LIG气候的理解：1）来自洞穴沉积物记录的新观测，2）现有湖芯的新U-Th测年，以及3）温度，降水和湿度的新半定量代理的应用，洞穴沉积物和湖泊沉积物。通过开发洞穴沉积物和湖泊沉积物的新的高分辨率代理时间序列，我们将为过去温暖时期北美季风的行为提供新的见解，并重建对倒数第二次冰消期（Termination II）和海洋同位素阶段5（MIS 5）期间突发气候事件的水文气候响应。该研究使用了由以前的NSF和USGS资助的大陆钻探项目恢复和存档的现有湖芯，以及最近收集的已知跨越MIS 5和LIG大部分的洞穴沉积物。潜在的更广泛的影响包括量化过去温暖时期的区域水文气候变化和末次间冰期气候模型模拟的基准。其他更广泛的影响包括通过召集水资源管理人员、政府机构（例如，本次研讨会将强调陆地过去的气候记录（湖泊沉积物，树木年轮，洞穴沉积物）可以提供的信息，这些信息超出了政策制定者评估气候变化和极端事件（如干旱和洪水）所需的仪器记录。研究人员将编写一份白色文件，为水资源管理人员编写政策简报，并在一次科学会议（美国地球物理联盟）的教育和宣传会议上发表演讲。该项目将为两名研究生和一名博士后研究员提供科学培训、指导和专业发展。通过联合实地考察和合作，这些学生和博士后将有机会发展气候档案，新颖的代理系统，地质年代学和模型代理比较的跨学科专业知识。此外，研究人员还将招募本科生完成与该项目相关的暑期实习。本科生将通过（1）地球地平线计划和范德比尔特大学与田纳西州州立大学（历史上的黑人大学）之间的合作关系招募;（2）布朗大学的领导联盟计划通过NSF-REU-EPSCOR资助。将鼓励本科生在区域，国家和国际科学会议（例如，该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。